The Camshaft angle in BMW vehicles is a key measurement, tracked by the Camshaft Position Sensor. This sensor helps the engine control unit (ECU) pinpoint the Camshaft’s position and timing, which is critical for engines with variable valve timing systems like VANOS.
Camshaft Angle at Idle
- In many BMW models, like the M52B28 engine in the E36 328i, the Camshaft angle is typically 16-20 degrees at idle.
Camshaft Angle During Revving
- As the engine RPM rises, the Camshaft angle changes. For the M52B28 engine, the Camshaft angle increases to about 40-45 degrees when the engine reaches 3-4k RPM.
Impact of Incorrect Camshaft Angle Readings
- Incorrect Camshaft angle readings or a lack of change with RPM can lead to noticeable engine issues:
- Poor throttle response
- Lack of power below 3.5k RPM
- Weak engine performance
- Possible batch firing of injectors, which may sound like ticking.
VANOS System and Camshaft Angle
- The correct Camshaft angle is crucial for the VANOS system to work properly. A faulty sensor can cause incorrect readings, which may prevent VANOS from functioning, leading to performance problems.
Replacing a Faulty Camshaft Sensor
- If a Camshaft sensor is faulty, replacing it with a genuine BMW part or a high-quality aftermarket option can fix the problem.
- Original BMW Camshaft sensors are often made by SWF (Valeo), Vemo, or AB Electronik. Reliable aftermarket brands like VNE or Hella are good alternatives for replacements.
Definition and Purpose
The Camshaft angle in BMW vehicles refers to the position of the Camshaft relative to the Crankshaft. This is especially important in models with the Variable Nockenwellen Steuerung (VANOS) system. VANOS enhances engine performance by adjusting the Camshaft timing, leading to better fuel efficiency, more power, and reduced emissions.
Purpose of the VANOS System:
- Improved Engine Performance: Adjusting the Camshaft angle helps optimize timing, boosting overall engine performance.
- Better Fuel Efficiency: VANOS fine-tunes Camshaft timing to reduce fuel consumption.
- Lower Emissions: Correct timing adjustments lead to cleaner combustion, reducing emissions.
Role of Camshaft Position Sensors:
- Synchronization: Camshaft Position Sensors send real-time data to the engine control module (DME) to ensure accurate timing between the Camshaft and Crankshaft.
- Valve Timing Control: This data allows the DME to manage valve timing precisely, ensuring smooth engine operation.
Specified Angle
In BMW engine management, the Specified Angle is key to optimizing engine performance. The Digital Motor Electronics (DME) calculates this angle based on the Crankshaft position and sensor data to achieve maximum efficiency.
- The Target Eccentric Shaft Angle is set by the DME depending on the engine’s state. For example, during startup, the DME adjusts the Eccentric Shaft to around 45 degrees for more throttle or valve lift. After startup, the angle drops to about 30 degrees, and further to 19-20 degrees during warm idle. It can rise to around 26 degrees when the compressor valve activates.
- This angle also affects injector timing. The “Angle Specifies” field sets the injector timing to “End of Squirt,” “Middle of Squirt,” or “Beginning of Squirt.” The default “End of Squirt” ensures fuel is injected precisely before the top dead center (TDC).
Impact of RPM on Injector Timing
RPM adjustments cause delays in fuel vaporization, as seen below: – 1000 RPM: 48 degrees – 2000 RPM: 96 degrees – 3000 RPM: 144 degrees – 4000 RPM: 192 degrees – 5000 RPM: 240 degrees – 6000 RPM: 288 degrees – 7000 RPM: 336 degrees
- Correctly setting the specified angle optimizes fuel atomization and engine efficiency. Adjusting injector timing by 30-40 degrees can significantly shift the Air-Fuel Ratio (AFR), so precise tuning is crucial for ideal performance.
Actual Angle of the Camshaft in BM3
The actual angle of the Camshaft refers to its precise position relative to the Crankshaft at any moment. This relationship is crucial for smooth engine operation. Below are key points about the Camshaft‘s actual angle:
Camshaft and Crankshaft Relationship
- The Camshaft rotates once for every two Crankshaft revolutions, maintaining a 1:2 ratio through the timing chain and sprockets. This ratio ensures proper timing of the engine’s intake and exhaust valves.
Degreeing the Camshaft
- To measure the actual angle, you need to find the Top Dead Center (TDC) of the #1 cylinder using a degree wheel, a stationary pointer, and a dial indicator. This process helps ensure the Camshaft’s position is measured accurately.
Deviations from Specification
- Incorrect Camshaft timing can cause engine problems like rough idling or misfires. For example, in a Porsche 996 engine, deviations of -12.53 degrees for Camshaft bank 1 and 3.05 degrees for Camshaft bank 2 were found, leading to misfires.
Correcting Camshaft Position
- The Camshaft’s position should ideally be close to 0.00 degrees. After adjusting the timing, the goal is to have 0.00 deviations for both Camshaft positions to ensure the engine runs properly.
Crankshaft Rotation and Rechecking
- After adjusting one Camshaft bank, rotate the Crankshaft 360 degrees before checking or adjusting the other bank. This step prevents errors in timing adjustments.
Iterative Adjustments and TDC
- To find TDC, rotate the Crankshaft until the piston reaches its highest point, then zero the dial indicator and take degree readings on both sides of TDC. If the readings aren’t symmetrical, make adjustments until the Camshaft is aligned correctly.
Final Calibration
- Once the Camshaft is aligned and deviations corrected, allow the DME (engine control unit) to relearn the new Camshaft settings. This helps the engine run optimally.
Reference Angle
The Reference Angle in a BM3 engine is the Camshaft angle when the solenoid is in its neutral state. This happens when oil pressure is equal on both sides of the VANOS piston.
Base Angle
The Reference Angle is the base angle, around which other important angles—such as the Actual Angle and the Specified Angle—vary during engine operation. These angles are measured relative to the Reference Angle.
Neutral Position
This angle can also be the Camshaft’s position when the engine is off, and the solenoid returns to neutral. In this state, the VANOS system does not actively adjust the Camshaft.
Oscillation
The Actual Angle and Specified Angle can shift positively or negatively from the Reference Angle, showing Camshaft movement during engine performance.
Diagnosing Issues
If the Actual and Specified angles are close to each other but far from the Reference Angle, it may indicate an issue with the VANOS system or Camshaft sensors. For example: – Inlet Actual Angle: 112.5° – Specified Angle: 112.2° – Reference Angle: 123.1°
This significant gap from the Reference Angle suggests the Camshaft may not be in the expected neutral state, possibly signaling a malfunction.
Comparison
If the Actual and Specified angles match closely, the Camshaft sensors and VANOS system are likely working well. However, large differences between these angles and the Reference Angle may need further inspection to prevent engine problems.
Flank Value
The flank value in Camshaft Position Sensors and engine timing refers to the difference between the actual and expected Camshaft positions. For instance, in a Porsche engine, an N050_Camshaft deviation of -3.00 degrees shows a 3-degree difference from the expected position on Bank 2.
Mechanical Timing Issues
- If physical inspection reveals that tools like the crank pin or flat bar don’t align with the Camshaft slots, it indicates a timing problem, possibly related to the flank value. Misalignment shows the Camshaft is not correctly positioned.
Electrical Integrity and Sensor Issues
- Check the Camshaft sensor wiring for any interruptions. Continuity between the sensor and the Engine Control Unit (DME) pins must be intact. Shorts or interference may cause Camshaft position deviations.
- If the Camshaft sensor provides an implausible signal, it may trigger error codes like P0341. A high or low signal can lead to P0342 or P0343 errors, which might also connect to the flank value deviation.
Testing and Replacing Camshaft Sensors
- Use a multimeter to check resistance across the sensor pins (set to 20k ohms) to verify the sensor condition. If there’s no reading, the sensor may be faulty and cause incorrect flank values.
- If the sensor is faulty, replacement and recalibration may be necessary. The CASE (Crank Angle Sensor Error) relearn procedure might also need to be done using an OBD-II scanner to reset the Camshaft position.
Diagnostic Use
Camshaft angle diagnostics in BM3 are essential for detecting issues with the VANOS system and Camshaft Position Sensors. A noticeable difference between the actual and specified Camshaft angles often indicates a malfunction.
Common Diagnostic Codes and Symptoms
- P1520, P1523, P1397: These codes suggest issues with the VANOS solenoids or Camshaft Position Sensors in engines like the N52, N54, N55, and N62.
- P0011 through P0025: Common in newer engines with dual VANOS and Valvetronic, these codes point to problems with the VANOS solenoids or Camshaft sensors.
- 2A82 and 2A87 Codes: Indicate faulty VANOS solenoids, which may need replacement.
- P0012 and P0015 Codes: These suggest issues with either the Camshaft Position Sensor (CMP) or the VANOS solenoids. Swapping the solenoids can help pinpoint the faulty part.
Diagnostic Procedures
- Camshaft Position Sensor Test:
- Use a voltmeter to check the signal and ground wires. A proper reading should show a 5-volt signal wire and a 12-volt wire. When a metal object is near the sensor, the voltage should drop to zero, indicating it works properly.
- If there’s no signal, the sensor might be faulty, or a fuse could be blown.
- Swapping VANOS Solenoids: Swap the intake and exhaust VANOS solenoids to check if one is faulty. Since they are interchangeable, this can narrow down or resolve the issue.
Tools and Cost
- BMW Scan Tool: A BMW-specific scan tool can provide detailed codes related to the VANOS system, helping to distinguish between solenoid and sensor issues.
- Replacement Costs: Genuine BMW VANOS solenoids cost around $300 each. Total replacement costs can vary—from as little as $20 for minor fixes to $1500 for more complex repairs.
By following these steps, you can effectively diagnose and resolve Camshaft angle problems in BM3 systems.
Regular diagnostic checks, such as testing the Camshaft Position Sensor and inspecting the VANOS solenoids, can help prevent performance issues like misfires, poor throttle response, and lack of power. If problems arise, timely sensor replacement and system calibration are essential for ensuring smooth operation.
For reliable Camshaft sensors and replacement parts, consider genuine BMW components or trusted aftermarket options from brands like SWF, Vemo, and Hella. Visit Volgen Power to explore high-quality engine parts, ensuring your BMW continues to perform at its best.